BERLIN (AP) — German police on Sunday released three British citizens who were taken into custody after their conversation during a flight to London prompted an easyJet pilot to make an unscheduled stop in Cologne.

Cologne police said in a statement that officers who questioned the men and examined their cellphones found no evidence they had planned an attack.

"At the moment Cologne police believe there was no actual threat," spokesman Christoph Gilles said.

According to police, a female passenger on the flight Saturday from the Slovenian capital Ljubljana overheard a conversation with "terrorist content" between the men, aged 31, 38 and 48.

One of them men also had a book with the word "kill" and a picture of a sniper rifle on it, police said.

The plane was diverted to Cologne-Bonn airport as a precaution and the 151 passengers on board were disembarked using emergency slides. Police carried out a "controlled explosion" on a rucksack belonging to one of the men that contained wires, but these turned out to be part of a charging device, Gilles said.

Several people were slightly injured during the plane's evacuation.